Speaker options

So i have a buddy that is looking to upgrade his speakers. The local dealers do have several options, but he wants to go to a specific dealer and all they have are DD, Soundstream, and cerwin vega. he is stuck between soundstream and cerwin vega. I had told him there are other options out there. Anyways the question is what are some decent speakers the sound great on just deck power, 15-50watts rms.